Yang San Yin Si: The Ancient Chinese Concept of Balance in the I Ching

The term “Yang San Yin Si” (阳三阴四) is a concept rooted in the study of the I Ching (易经) during the Han Dynasty. Confucius famously said, “Yang San Yin Si, wei zhi zheng ye” (阳三阴四，位之正也), which translates to, “Yang is in the third position, Yin in the fourth, and this is the proper arrangement.” This suggests that “Yang San Yin Si” refers to a standard or basis for positioning elements, such as the forces of Yin and Yang.

In the Western Han Dynasty, the scholar Jing Fang (京房) formulated the idea of “Yang San Yin Si” when he was summarizing the hexagrams of the I Ching. He argued that the number three represents the East, the direction from which the sun rises, and therefore is a “Yang” number, while four represents the West, where the sun sets, and thus is an “Yin” number. The boundary between Yin and Yang is determined by these two numbers—three and four. As the Jing Shi Yi Chuan (京氏易传) explains, “Confucius said: ‘Yang San Yin Si, wei zhi zheng ye.’ Three represents the East, where the sun rises. It is round and opens in three directions. Four represents the West, where the sun sets. It is square and forms four directions. This is the way the sun and moon move through heaven. Thus, the sixty-four hexagrams of the I Ching are divided into two halves, representing Yin and Yang.”

The passage continues: “The odd and even numbers are derived from Heaven and Earth. Heaven and Earth are the roots of Yin and Yang, while the trigrams Kan (坎) and Li (离) represent their essential natures. The system of the I Ching divides into four groups, forming a framework for the hexagrams. With eighteen variations, it creates sixty-four hexagrams. These hexagrams indicate good or bad fortune, and through them, the Five Elements are harmonized. If the energy follows the right path, it is auspicious; if it goes against the flow, it is inauspicious.”

In addition to this, looking at the structure of the hexagrams, there are six lines in each hexagram. The three upper lines represent the Yang aspect of Heaven, while the four lower lines represent the Yin aspect of Earth. The boundary between these two realms is formed by the third and fourth lines, thus becoming the limit of Yin and Yang. This concept of “Yang San Yin Si” is rooted in the natural world and cosmic order.

Expanding upon this idea, one can conclude that both Heaven and Earth have their own corresponding numbers, and all elements of the I Ching—from the eight trigrams to the sixty-four hexagrams—are structured around this central point. As the Zhou Yi·Xi Ci (周易·系辞) states, “The extremes of numbers determine the patterns of the universe.” The Yi Wei·Qian Zuo Du (易纬·乾凿度) also expands on the understanding of the sixty-four hexagrams in the I Ching: “Confucius said: ‘Yang San Yin Si, wei zhi zheng ye.’ Therefore, the sixty-four hexagrams are divided into two halves, representing Yin and Yang. The Yang path is pure and odd, which is reflected in the upper thirty hexagrams, representing Yang. The Yin path is impure and irregular, so the lower thirty-four hexagrams represent Yin.”

This shows that the upper trigrams (the first thirty hexagrams) are Yang, while the lower trigrams (the last thirty-four hexagrams) represent Yin. Although later scholars have debated this view, it had a significant influence during its time.

The Balance of Light and Shadow

In a small town in the American Midwest, there was a boy named Ethan, a young philosophy student who spent his days trying to make sense of the world. Ethan had always been fascinated by the concept of balance—the way everything in life seemed to have its opposite, its counterweight. He had learned this early, through his love of nature. For instance, the sun was powerful and bright, but it could only shine because the night, with its deep darkness, provided the contrast. The moon, in all its quiet beauty, followed this same rhythm—never as overpowering as the sun, but essential nonetheless.

One evening, while scrolling through his professor’s old lecture notes, Ethan stumbled upon something that intrigued him: an ancient Chinese philosophy that talked about the balance between two forces—Yin and Yang. He remembered hearing the term before but never fully grasped it. The notes mentioned something called “Yang San Yin Si”—a phrase from the I Ching, a classic text of ancient wisdom.

Ethan wasn’t the type to dive into obscure teachings without reason, but something about the phrase called to him. It was as if the universe itself was nudging him to explore deeper.

As he read on, the notes explained that “Yang San Yin Si” referred to the third and fourth positions in a specific numerical system used to map out the cosmos. The third position represented the East, where the sun rose—pure, bright, and full of life. The fourth position represented the West, where the sun set—quiet, restful, and still. The balance between these two positions was essential, the perfect harmony between light and darkness, creation and rest.

This idea lingered in Ethan’s mind for days. It reminded him of the tension he felt between his ambitious dreams and his deep need for peace and stillness.

His life was a whirlwind of expectations. As the son of a successful businessman, Ethan often felt pressure to follow a certain path. His father had carved out a life of constant motion and achievement, a life where the sun never seemed to set. Ethan, however, felt an internal pull towards a quieter, slower pace—the West, where the sun dipped into the horizon, offering a chance to breathe.

But the conflict between these two forces was starting to eat at him. He felt torn between the bright, relentless drive of his father’s world (the Yang) and his yearning for peace and simplicity (the Yin). There was a gnawing emptiness inside him, a feeling that something was missing, but he didn’t know what it was.

It all came to a head one evening when Ethan had to decide whether to accept a prestigious internship at a fast-paced tech company in New York City. His father was thrilled, insisting that this was Ethan’s chance to make his mark, to “rise with the sun.” But Ethan felt a deep unease. It wasn’t just the fear of change; it was something deeper—a sense of imbalance.

That night, he sat by the window, staring at the sky as the sun began to set. The familiar warmth of the day gradually gave way to the cool embrace of evening. It was then that he recalled the words of the I Ching: “Yang San Yin Si.” The third and fourth positions. The boundary between the forces of light and shadow. He realized that the lesson wasn’t just about philosophy; it was about his life. The East and the West, the Yang and the Yin, weren’t in opposition—they needed each other to create harmony.

The third and fourth positions were a boundary, yes, but also a place of integration. The sun couldn’t rise without setting, and the moon couldn’t shine without the dark sky. He needed both parts—his ambition and his need for peace—to move forward.

Ethan called his father the next morning. “I’ve decided to take a different path,” he said, his voice steady despite the storm of emotions inside. “I’m going to work in a place that allows me to focus on the balance of my life—not just the hustle.”

His father’s silence was long, but eventually, he spoke. “I understand,” he said softly, his voice carrying a mix of pride and regret. “It’s not an easy choice, but it’s yours to make. Just remember, you can’t find balance if you don’t know when to stop moving.”

And with that, Ethan felt the weight of the decision lift. He wasn’t choosing between the East and the West, between ambition and rest. He was learning how to integrate both, creating his own rhythm between the two.

The emotional tension he had lived with for so long—this internal conflict between Yang and Yin—began to resolve, not by choosing one side over the other, but by allowing both forces to coexist.

As the sun set that evening, Ethan knew that he had found his balance. He had come to understand that the boundary between the two—just like the “Yang San Yin Si”—was not an edge to be feared, but a place of transformation. The night, after all, was just the other side of the day.